1. Field of the Invention
This invention relates to a fertility period calculator and specifically to an improved fertility calculator especially useful in third world countries to determine, through the natural menstrual cycle of a woman, those particular days when a woman is most likely not to conceive a child. The device is simplified for use by women who might otherwise have difficulty in comprehending and manipulating a complicated device.
2. Description of the Prior Art
Fertility period calculators are well known in the prior art. U.S. Pat. No. 4,092,521, issued to Weisshaar, May 30, 1978, shows a multiple disk device that is used to calculate the menstrual cycle. Because of the numerous disks and written materials on the device it is complicated to determine the specific available days when conception is not likely. U.S. Pat. No. 4,367,527, issued to Desjacques, Jan. 4, 1983, shows an electronic calculator including memory that is quite complex and would be difficult for many people in the third world to utilize effectively. Another fertility calculator is shown in U.S. Pat. No. 4,625,099, issued to Freedom, Nov. 25, 1986 which contains much written data and disk-like rotatable members which require a thorough knowledge of written language for proper utilization. U.S. Pat. No. 4,737,619, issued to Freedom, Apr. 12, 1988, shows a handheld calculator having only two disks but still requires reading of written indicia for complete understanding and utilization of the device. Finally, U.S. Pat. No. 3,964,674, issued to Van der Gahst, Jun. 22, 1976, shows a very complex calculator with multiple disks and much indicia which may be difficult for persons with limited education to utilize effectively.
Another important factor in the utilization of fertility period calculators is their universal distribution in numerous countries having different languages. The present invention provides a very simple mechanical fertility period calculator that requires only two manipulations and uses universal symbols to aid the user without requiring complex written indicia instructions for its operation. The device is also mounted in a protective compact housing which can be carried and stored safely and conveniently.